TP53 and thyroid cancer: In agreement, Zeki et al. transfected a p53-deficient thyroid cancer cell line (FRO) with wild-type TP53 and found that p53 was implicated in the re-expression of the major-histocompatibility-complex (MHC)-class-II antigen, and consequently the MHC-class-II-associated stimulation of CD4+ cytotoxic T cells.